gcc/libstdc++-v3/include/ext/malloc_allocator.h

// Allocators -*- C++ -*-

// Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

/*
 * Copyright (c) 1996-1997
 * Silicon Graphics Computer Systems, Inc.
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Silicon Graphics makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 */

/** @file ext/debug_allocator.h
 *  This file is a GNU extension to the Standard C++ Library. 
 *  You should only include this header if you are using GCC 3 or later.
 */

#ifndef _MALLOC_ALLOCATOR_H
#define _MALLOC_ALLOCATOR_H 1

#include <bits/allocator_traits.h>

namespace __gnu_cxx
{
  /**
   *  @if maint
   *  A malloc-based allocator.  Typically slower than the
   *  __pool_alloc (below).  Typically thread-safe and more
   *  storage efficient.  The template argument is unused and is only present
   *  to permit multiple instantiations (but see __pool_alloc
   *  for caveats).  "SGI" style, plus __set_malloc_handler for OOM conditions.
   *  @endif
   *  (See @link Allocators allocators info @endlink for more.)
   */
  template<int __inst>
    class __malloc_alloc
    {
    private:
      static void* _S_oom_malloc(size_t);
      static void (* __malloc_alloc_oom_handler)();

    public:
      static void*
      allocate(size_t __n)
      {
        void* __result = malloc(__n);
        if (__builtin_expect(__result == 0, 0))
	  __result = _S_oom_malloc(__n);
        return __result;
      }

      static void
      deallocate(void* __p, size_t /* __n */)
      { free(__p); }

      static void (* __set_malloc_handler(void (*__f)()))()
      {
        void (* __old)() = __malloc_alloc_oom_handler;
        __malloc_alloc_oom_handler = __f;
        return __old;
      }
    };

  // malloc_alloc out-of-memory handling
  template<int __inst>
    void (* __malloc_alloc<__inst>::__malloc_alloc_oom_handler)() = 0;

  template<int __inst>
    void*
    __malloc_alloc<__inst>::
    _S_oom_malloc(size_t __n)
    {
      void (* __my_malloc_handler)();
      void* __result;

      for (;;)
        {
          __my_malloc_handler = __malloc_alloc_oom_handler;
          if (__builtin_expect(__my_malloc_handler == 0, 0))
            __throw_bad_alloc();
          (*__my_malloc_handler)();
          __result = malloc(__n);
          if (__result)
            return __result;
        }
    }
  //@{
  /** Comparison operators for all of the predifined SGI-style allocators.
   *  This ensures that __allocator<malloc_alloc> (for example) will work
   *  correctly.  As required, all allocators compare equal.
   */
  template<int inst>
    inline bool
    operator==(const __malloc_alloc<inst>&, const __malloc_alloc<inst>&)
    { return true; }

  template<int __inst>
    inline bool
    operator!=(const __malloc_alloc<__inst>&, const __malloc_alloc<__inst>&)
    { return false; }
  //@}
} // namespace __gnu_cxx

namespace std
{
  //@{
  /// Versions for the predefined "SGI" style allocators.
  template<typename _Tp, int __inst>
    struct _Alloc_traits<_Tp, __gnu_cxx::__malloc_alloc<__inst> >
    {
      static const bool _S_instanceless = true;
      typedef __gnu_cxx:: __malloc_alloc<__inst>	base_alloc_type;
      typedef __simple_alloc<_Tp, base_alloc_type>	_Alloc_type;
      typedef __allocator<_Tp, base_alloc_type>		allocator_type;
    };
  //@}

  //@{
  /// Versions for the __allocator adaptor used with the predefined
  /// "SGI" style allocators.
  template<typename _Tp, typename _Tp1, int __inst>
    struct _Alloc_traits<_Tp, __allocator<_Tp1, 
					  __gnu_cxx::__malloc_alloc<__inst> > >
    {
      static const bool _S_instanceless = true;
      typedef __gnu_cxx:: __malloc_alloc<__inst>	base_alloc_type;
      typedef __simple_alloc<_Tp, base_alloc_type>	_Alloc_type;
      typedef __allocator<_Tp, base_alloc_type>		allocator_type;
    };
  //@}
} // namespace std

#endif